Optical Fiber Humidity Sensor With Porous TiO&lt;sub&gt;2&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt;/TiO&lt;sub&gt;2&lt;/sub&gt; Coatings on Fiber Tip

Huang, Chujia; Xie, Weijing; Lee, Dongwen; Qi, Chongjie; Yang, Minghong; Wang, Min; Tang, Jianguan

doi:10.1109/lpt.2015.2426726

Cited by 35 publications

(12 citation statements)

References 16 publications

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“…Other humidity-sensitive materials used in FPIs include semiconductors [77,79], ceramics [80], polymers [81,82], etc. Porous anodic alumina has been studied and a sensitivity of 0.31 nm/%RH was achieved [80].…”

Section: Recent Trends In Optical Fiber Humidity Sensorsmentioning

confidence: 99%

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Recent Developments in Fiber Optics Humidity Sensors

Ascorbe

Corres

Arregui

et al. 2017

Sensors

201

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A wide range of applications such as health, human comfort, agriculture, food processing and storage, and electronic manufacturing, among others, require fast and accurate measurement of humidity. Sensors based on optical fibers present several advantages over electronic sensors and great research efforts have been made in recent years in this field. The present paper reports the current trends of optical fiber humidity sensors. The evolution of optical structures developed towards humidity sensing, as well as the novel materials used for this purpose, will be analyzed. Well-known optical structures, such as long-period fiber gratings or fiber Bragg gratings, are still being studied towards an enhancement of their sensitivity. Sensors based on lossy mode resonances constitute a platform that combines high sensitivity with low complexity, both in terms of their fabrication process and the equipment required. Novel structures, such as resonators, are being studied in order to improve the resolution of humidity sensors. Moreover, recent research on polymer optical fibers suggests that the sensitivity of this kind of sensor has not yet reached its limit. Therefore, there is still room for improvement in terms of sensitivity and resolution.

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Section: Recent Trends In Optical Fiber Humidity Sensorsmentioning

confidence: 99%

“…Previous FPIs were based on changes in the RI of the material due to the water absorbed into the pores [80] and/or onto the metal oxide surface [77,79]. Water-swelling materials change their dimensions when they are subjected to changes of RH.…”

Section: Recent Trends In Optical Fiber Humidity Sensorsmentioning

confidence: 99%

Recent Developments in Fiber Optics Humidity Sensors

Ascorbe

Corres

Arregui

et al. 2017

Sensors

201

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“…The humidity sensors research has generated a wide variety of devices composed of polymers, ceramics, blended materials, graphene (G)-based materials, and others [2,5,6,7,8,9,10,11,12,13,14]. The humidity level is obtained by measurement of either the electrical resistance or capacitance of the sensing material [4].…”

Section: Introductionmentioning

confidence: 99%

A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

Hernández-Rivera

Rodríguez-Roldán

Mora-Martínez

et al. 2017

Sensors

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Humidity sensors have been widely used in areas such as agriculture, environmental conservation, medicine, instrumentation and climatology. Hydrophobicity is one of the important factors in capacitive humidity sensors: recent research has shown that the inclusion of graphene (G) in polyvinylidene fluoride (PVDF) improves its hydrophobicity. In this context, a methodology to fabricate electrospun membranes of PVDF blended with G was developed in order to improve the PVDF properties allowing the use of PVDF/G membrane as a capacitive humidity sensor. Micrographs of membranes were obtained by scanning electron microscopy to analyze the morphology of the fabricated samples. Subsequently, the capacitive response of the membrane, which showed an almost linear and directly proportional response to humidity, was tested. Results showed that the response time of PVDF/G membrane was faster than that of a commercial DHT11 sensor. In summary, PVDF/G membranes exhibit interesting properties as humidity sensors.

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“…The total reflection intensity due to the Fabry-Perot cavity created by the film deposited onto the tip of the fibre can be explained as follows: 1) the presence of two optical interfaces (fibre-film and film-air), each with its characteristic Fresnel coefficients for reflection, leads to a division of the incident beam into two main back reflections (higher-order reflections between the interfaces can be neglected), and the optical fibre sensor behaves as a Fabry-Perot interferometer of low finesse [10], [11]; 2) loss factors and coefficients associated with losses are due to optical absorption and scattering of the beam by interfaces and film itself; 3) changes in total optical reflection are due to changing the optical thickness of the film (the product  f * L ). The reflection spectrum will change when the geometrical thickness (L) increases by means of either the number of film layers deposited on the tip or the swelling due to water absorption [8].…”

Section: Introductionmentioning

confidence: 99%

“…The reflection spectrum will change when the geometrical thickness (L) increases by means of either the number of film layers deposited on the tip or the swelling due to water absorption [8]. The response in the total optical intensity reflected can also be modulated by adsorption and absorption of water vapour molecules by means of changing the effective refractive index of the film ( f ), following the Bruggeman effective medium model criteria [11].…”

Section: Introductionmentioning

confidence: 99%

Characterization and Use of a Fiber Optic Sensor Based on PAH/SiO₂ Film for Humidity Sensing in Ventilator Care Equipment

Hernández

Morgan

Hayes-Gill

et al. 2016

IEEE Trans. Biomed. Eng.

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The user has requested enhancement of the downloaded file. IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING 1 Abstract-Objective: To develop a compact probe that can be used to monitor humidity in ventilator care equipment. A mesoporous film of alternate layers of Poly(allylamine hydrochloride) (PAH) and silica (SiO 2 ) nanoparticles (bilayers), deposited onto an optical fibre was used. The sensing film behaves as a Fabry-Perot cavity of low-finesse where the absorption of water vapour changes the optical thickness and produces a change in reflection proportional to humidity. Methods: The mesoporous film was deposited upon the cleaved tip of an optical fibre using the layer-by-layer method. The sensor was calibrated in a bench model against a commercially available capacitive sensor. The sensitivity and response time were assessed in the range from 5 % relative humidity (RH) to 95 %RH for different numbers of bilayers up to a maximum of nine. Results: The sensitivity increases with the number of bilayers deposited; sensitivity of 2.28 mV/%RH was obtained for nine bilayers. The time constant of the response was 1.13 s ± 0.30 s which is faster than the commercial device (measured as 158 s). After calibration, the optical fibre humidity sensor was utilised in a bench top study employing a mechanical ventilator. The fast response time enabled changes in humidity in individual breaths to be resolved. Conclusion: Optical fibre sensors have the potential to be used to monitor breath to breath humidity during ventilator care. Significance: Control of humidity is an essential part of critical respiratory care and the developed sensor provides a sensitive, compact and fast method of humidity monitoring.Index Terms-Humidity sensor, relative humidity, FabryPerot, layer-by-layer (LbL), intensive care unit, critical care, optical fibre sensor.

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Optical Fiber Humidity Sensor With Porous TiO<sub>2</sub>/SiO<sub>2</sub>/TiO<sub>2</sub> Coatings on Fiber Tip

Cited by 35 publications

References 16 publications

Recent Developments in Fiber Optics Humidity Sensors

Recent Developments in Fiber Optics Humidity Sensors

A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

Characterization and Use of a Fiber Optic Sensor Based on PAH/SiO₂ Film for Humidity Sensing in Ventilator Care Equipment

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Optical Fiber Humidity Sensor With Porous TiO<sub>2</sub>/SiO<sub>2</sub>/TiO<sub>2</sub> Coatings on Fiber Tip

Cited by 35 publications

References 16 publications

Recent Developments in Fiber Optics Humidity Sensors

Recent Developments in Fiber Optics Humidity Sensors

A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

Characterization and Use of a Fiber Optic Sensor Based on PAH/SiO2 Film for Humidity Sensing in Ventilator Care Equipment

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Product

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Characterization and Use of a Fiber Optic Sensor Based on PAH/SiO₂ Film for Humidity Sensing in Ventilator Care Equipment